WO 03/106202 A1 describes a suspension device of the general type of the present invention including a damping device having a separate circuit of a hydraulic damping medium which is independent of the spring cylinder and the spring medium. For this purpose, at least one separate damping cylinder having a damper piston which is guided in a cylinder so as to be movable in the cylinder is required, as well as at least one damping valve which is connected hydraulically to the damper cylinder. The piston of the spring cylinder is driven via a drive device which is formed by a gear mechanism which converts the pivoting movements of a wheel strut supporting arm into the linear relative movements between the cylinder and the piston of the spring cylinder. Here, the damping device is to interact with the same drive device as the spring cylinder, the media (spring and damping medium) being completely separate from one another. A reason for this is that the system provides thermal independence as a result, and therefore damping-induced heating of the damping medium is not critical to the extent that the temperature of the spring medium and thus also the pressure and the pressure-dependent supporting spring force remain unaffected by such heating. In contrast to this, heating of the spring medium would also bring about a change in the pressure and thus in the supporting spring force. The known suspension and damping device has a relatively complicated construction, however, which also becomes apparent by a relatively large installation volume and weight.
Furthermore, customary telescopic spring cylinders are also known, often also referred to as “spring struts”, which are mounted directly between the wheel or wheel strut and the vehicle frame. In the case of a hydropneumatic design of spring struts of this type, a hydraulic medium is displaced on one side against a compressible medium, and at the same time this hydraulic flow is also guided via an integrated damping valve. However, the hydraulic medium is heated rapidly and to a certain extent severely as a result of the damping (throttling). This heating has an effect on the compressible, in particular pneumatic medium, in that the pressure of the latter and thus also the supporting spring force rise. Unfavorable, widely varying suspension and damping properties result from this thermal effect.